1. Field of the Invention
The present invention relates to a concrete pole such as an electric pole, and more particularly, to a concrete pole having elasticity improved by reinforcement.
2. Prior Art
Concrete poles are widely used for many electric poles including those for power distribution in urban areas, and those for power supply for electric trains. In general, a concrete pole is formed into a hollow cylindrical structure made of reinforced concrete by using a cage of reinforcing bars formed into a substantially cylindrical shape and placing concrete by centrifugal casting in and outside this cage.
When an automobile collides with a concrete pole on the road, the concrete pole deflects once and then resumes its original vertical posture by elasticity. When the impact is strong and results in a large deflection, however, the reinforcing bars in the interior are plastically deformed with an elongation of only 0.2%. The concrete pole can not resume the original posture, remaining as deformed.
The deformed concrete pole thus forms a traffic hindrance, and poses a danger.
Under such circumstances as described above, there is a demand for a concrete pole having an improved elasticity, which, even after occurrence of such a large deflection as to cause plastic deformation of reinforcing bars therein, can resume the original vertical posture, and which does not form a traffic hindrance or a danger for cars and electric trains. A concrete pole provided with such properties has not as yet been proposed.